JP2006049407A - Manufacturing method of compound soft magnetic material having high strength and high specific resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a compound soft material having high strength and high specific resistance. <P>SOLUTION: A plasma processing is performed for previously applying liquid where one type or two or above types among polyether sulfone, polyphenylene sulphide, polyamideimide, polyimide and silicone resin and polytetrafluoroethylene are dissolved or distributed on a surface of iron powder or phosphate coating iron powder and drying it. 0.1 to 1.5 mass% of fluororesin powder is added and mixed to phosphate coating iron powder to which the plasma processing is performed. Mixed powder is formed, mixed powder is compressed and molded, and heat treatment is performed on it at a temperature of 320 to 450°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for efficiently producing a composite soft magnetic material having a complex shape, such as a motor core, an actuator, a magnetic sensor, an injector component, an ignition component, and a solenoid valve core, and having high strength and high specific resistance. is there.

In general, a composite soft magnetic material is manufactured by adding a resin powder to a soft magnetic powder such as iron or an iron alloy, mixing to prepare a mixed powder, compression-molding the mixed powder, and then performing a heat treatment. Are known. As the resin powder used at this time, in general, thermosetting phenol resin powder, thermoplastic polyamide resin powder, epoxy resin powder, polyimide resin powder, polyphenyl sulfide resin powder, etc. are often used, but fluororesin powder is used. It is also known. It is said that this fluororesin powder is easy to obtain an ultrafine powder, and the resin can be sintered at a temperature equal to or higher than the melting point of the resin, so that a dense insulating film is easily obtained (see Patent Document 1).
Furthermore, thermoplastic polyimide powder or a mixed powder of thermoplastic polyimide powder and polytetrafluoroethylene powder is added to atomized iron powder or iron powder having a phosphate film formed on the surface (hereinafter referred to as phosphate-coated iron powder). There is also known a method for producing a composite soft magnetic material in which a mixed powder is compression-molded and then subjected to heat treatment (see Patent Document 2).
JP 59-50138 A Japanese Patent Laid-Open No. 2004-71860

A method for producing a composite soft magnetic material according to Patent Document 1, in which a fluororesin powder is added to and mixed with a soft magnetic powder such as iron or an iron alloy, and a mixed powder is produced. Since the fluororesin powder is excellent in lubricity, the mixed powder obtained by adding the fluororesin powder to the soft magnetic powder such as iron or iron alloy and mixing is excellent in lubricity. Since it can be compression-molded without applying a lubricant to the inner surface of the mold, the step of applying the lubricant to the inner surface of the mold can be omitted, and the composite soft magnetic material can be produced efficiently. However, the composite soft magnetic material obtained by compression molding and heat treatment of a mixed powder obtained by mixing this fluororesin powder with soft magnetic powder such as iron or iron alloy is soft magnetic powder such as iron or iron alloy for fluororesin. Dense Sex is sufficient mechanical strength can not be obtained for bad.
On the other hand, Patent Document 2 in which a thermoplastic powder or a mixed powder of thermoplastic polyimide powder and polytetrafluoroethylene powder is added to atomized iron powder or phosphate-coated iron powder and mixed and then heat-treated after compression molding. The method for producing the composite soft magnetic material described above is that a high-strength composite soft magnetic material is obtained because thermoplastic polyimide powder or thermoplastic polyimide powder is excellent in adhesion to atomized iron powder or phosphate-coated iron powder. However, since the mixed powder contains thermoplastic polyimide powder or thermoplastic polyimide powder, the lubrication characteristics of polytetrafluoroethylene powder are not sufficiently exhibited, so that the lubricant is applied to the inner surface of the mold space during compression molding. However, parts with complicated shapes such as motor yokes, especially thin parts In the molding of the parts to be performed, the lubricant may not be sufficiently applied to every corner of the inner surface of the mold space, and if there is an insufficient application of such lubricant, the resulting compression molded body will be scratched. Defects such as cracks may occur.

Accordingly, the present inventors have made a composite soft magnetic material having a higher strength and a higher specific resistance by compressing and heat-treating iron powder or phosphate-coated iron powder without applying a lubricant to the inner surface of the mold. As a result of research to develop a method of manufacturing
Apply a primer treatment to the surface of the iron powder or phosphate-coated iron powder in advance, add the fluororesin powder to the primer-treated iron powder or phosphate-coated iron powder, and mix to make a mixed powder. When the mixed powder is compression molded and heat treated, the adhesion between the iron powder or phosphate-coated iron powder and the resin is improved by applying a primer treatment, and a composite soft magnetic material having high strength and high specific resistance is obtained. When the mixed powder produced by adding and mixing fluororesin powder to iron powder or phosphate-coated iron powder that has been further treated with primer is compression molded, the mixed powder contains fluororesin powder. The lubricity is improved, and a compression-molded body having a complicated shape can be produced without applying a lubricant to the inner surface of the mold. Therefore, a complex magnetic material having a complicated shape can be efficiently produced. Results of studies say is that obtained.

The present invention has been made based on such research results,
(1) The surface of the iron powder or phosphate-coated iron powder is subjected to a primer treatment in advance, and the fluororesin powder is added to and mixed with the phosphate-coated iron powder subjected to the primer treatment to produce a mixed powder. It is characterized by a method for producing a composite soft magnetic material having high strength and high specific resistance, in which a mixed powder is compression-molded and then heat-treated.

In the primer treatment, a liquid in which polytetrafluoroethylene and one or more of polyethersulfone, polyphenylene sulfide, polyamideimide, polyimide, and silicone resin and polytetrafluoroethylene are dissolved or dispersed is applied to the surface of iron powder or phosphate-coated iron powder. It is a process of applying and drying. Therefore, the present invention
(2) A liquid in which one or more of polyethersulfone, polyphenylene sulfide, polyamideimide, polyimide, silicone resin and polytetrafluoroethylene are dissolved or dispersed in advance is applied to the surface of the iron powder or phosphate-coated iron powder. Applying a primer treatment to dry, and then adding the fluororesin powder to the phosphate-coated iron powder that has been subjected to the primer treatment to produce a mixed powder. It is characterized by a method for producing a composite soft magnetic material having a high specific resistance.

When the fluororesin powder is added to the primer-treated iron powder or phosphate-coated iron powder and the amount of the fluororesin powder is less than 0.1% by mass, sufficient lubricity cannot be obtained during compression molding. Therefore, it is not preferable because compression molding cannot be performed without applying a lubricant to the inner surface of the mold. On the other hand, if the content exceeds 1.5% by mass, the lubricity is improved, but the resin becomes too much. This is not preferable because the density of the composite soft magnetic material is reduced. Therefore, it is preferable that the amount of the fluororesin powder added to the primer-treated iron powder or phosphate-coated iron powder is in the range of 0.1 to 1.5% by mass. Therefore, the present invention
(3) A liquid in which one or more of polyethersulfone, polyphenylene sulfide, polyamideimide, polyimide, silicone resin and polytetrafluoroethylene are dissolved or dispersed in advance is applied to the surface of the iron powder or phosphate-coated iron powder. Then, apply the primer treatment to dry, and then add phosphate resin: 0.1-1.5% by mass to the phosphate-coated iron powder that has been subjected to this primer treatment to produce a mixed powder, and then compress this mixed powder. It is characterized by a method for producing a composite soft magnetic material having high strength and high specific resistance, which is heat-treated after being molded.

The heat treatment is preferably performed by heating within a temperature range of 320 to 450 ° C. If the heat treatment temperature is less than 320 ° C., the adhesion between the surface of the iron powder or phosphate-coated iron powder and the primer layer, the primer layer and the fluororesin becomes insufficient, and the mechanical strength of the composite soft magnetic material decreases. On the other hand, if it exceeds 450 degrees, the thermal decomposition of the fluororesin becomes remarkable and the mechanical strength of the composite soft magnetic material is lowered, which is not preferable. Therefore, the present invention
(4) A liquid in which one or more of polyethersulfone, polyphenylene sulfide, polyamideimide, polyimide, silicone resin and polytetrafluoroethylene are dissolved or dispersed is applied to the surface of iron powder or phosphate-coated iron powder in advance. Then, apply the primer treatment to dry, and then add phosphate resin: 0.1-1.5% by mass to the phosphate-coated iron powder that has been subjected to this primer treatment to produce a mixed powder, and then compress this mixed powder. It is characterized by a method for producing a composite soft magnetic material having high strength and high specific resistance, which is heat-treated at a temperature of 320 to 450 ° C. after molding.

Even if iron powder or phosphate-coated iron powder is compression-molded without applying a lubricant to the inner surface of the mold, a compression-molded body with a complicated shape can be produced without causing defective products, and the resulting compression It is possible to efficiently produce a complex soft magnetic material having a complex shape with high strength and specific resistance by heat-treating the compact.

  As raw materials, an atomized iron powder having an average particle diameter of 80 μm and a commercially available phosphate-coated iron powder having an average particle diameter of 100 μm were prepared. Furthermore, a polyethersulfone resin, a polyamideimide resin, a polyimide resin, a polyphenylene sulfide resin powder having an average particle size of 15 μm, and a room temperature curable liquid silicone resin were prepared. Furthermore, polytetrafluoroethylene powder having an average particle size of 0.3 μm was prepared as a fluororesin.

Example 1
Polyethersulfone resin is dissolved in N-methylpyrrolidone, and polytetrafluoroethylene powder and atomized iron powder are added to this solution and stirred to disperse, and dried while stirring to prime the surface of atomized iron powder. Then, a primer-treated atomized iron powder having the composition shown in Table 1 was produced.
A polytetrafluoroethylene resin powder was added to the primer-treated atomized iron powder at a ratio shown in Table 1 and mixed to prepare a mixed powder. The mixed powder is filled in the inner space of the mold having an outer diameter of 35 mm, an inner diameter of 30 mm, and a depth of 25 mm without applying the lubricant to the inner surface of the mold, and is compressed by compression molding at a pressure of 780 MPa. After preparing a 10 mm compression molded body and examining the presence or absence of defective products of the compression molded body, the compression molded body was heat-treated in the atmosphere at a temperature shown in Table 1 to achieve the method 1 of the present invention. Carried out.
The ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by the method 1 of the present invention was measured for the crushing strength at room temperature by using the Archimedes method using a universal testing machine. The density, the specific resistance of the C-shaped test piece obtained by dividing the ring-shaped test piece into two parts, and the magnetic flux density were measured using a BH loop tracer after winding, and the measurement results are shown in Table 1.

Comparative Example 1
A compression-molded article was produced by compression-molding the primed atomized iron powder produced in Example 1 in the same manner as in Example 1 without adding polytetrafluoroethylene resin powder. After the presence or absence of this, the compression molding was subjected to a heat treatment for holding the compressed molded body at a temperature shown in Table 1 in the atmosphere, and Comparative Method 1 was performed.
With respect to the ring-shaped composite soft magnetic material test piece having the outer diameter of 35 mm, the inner diameter of 30 mm, and the height of 10 mm produced by Comparative Method 1, the crushing strength, density, specific resistance and magnetic flux density were measured in the same manner. The measurement results are shown in Table 1.

Conventional Example 1
By blending and mixing polytetrafluoroethylene resin powder, which is a fluororesin powder, with atomized iron powder at a ratio shown in Table 1, a mixed powder is prepared, and this mixed powder is compression-molded in the same manner as in Example 1. A compression molded body was prepared, and the presence or absence of a defective product of the compression molded body was examined. After that, heat treatment was performed to keep the compression molded body at the temperature shown in Table 1 in the atmosphere, and the conventional method 1 was carried out.
A ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm manufactured by the conventional method 1 was used in the same manner as in Example 1 to obtain the crushing strength, density, specific resistance, and magnetic flux density. The measurement results are shown in Table 1.

  From the results shown in Table 1, the present invention method 1 is capable of producing a composite soft magnetic material having no defects in the compression molded body obtained compared to the comparative method 1 and having superior strength compared to the conventional method 1. I understand that I can do it.

Example 2
Polyphenylene sulfide resin powder, polytetrafluoroethylene powder and atomized iron powder were added to ethanol and dispersed by stirring, dried while stirring, and the dried powder was agglomerated after being kept at 350 ° C. in the atmosphere for 30 minutes. By pulverizing the powder, the surface of the atomized iron powder was subjected to a primer treatment to prepare a primer-treated atomized iron powder having the composition shown in Table 2.
Polytetrafluoroethylene resin powder was added to the primed atomized iron powder at a ratio shown in Table 2 and mixed to prepare a mixed powder. By filling this mixed powder into a mold inner space having dimensions of an outer diameter of 35 mm, an inner diameter of 30 mm, and a depth of 25 mm without applying the lubricant to the inner surface of the mold, and compression molding at a pressure of 780 MPa. A compression molded body having a height of 10 mm was prepared, and the presence or absence of a defective product of the compression molded body was examined. After that, the compression molded body was subjected to a heat treatment for maintaining the compression molded body at the temperature shown in Table 2 in the present invention. 2 was carried out.
The ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by the method 2 of the present invention was measured for the crushing strength at room temperature by using the Archimedes method using a universal testing machine. The density was measured for the C-shaped test piece obtained by dividing the ring-shaped test piece in two by the four-terminal method, and the magnetic flux density was measured by applying a winding and a BH loop tracer. The results are shown in Table 2.

Comparative Example 2
A compression-molded article was produced by compression-molding the primed atomized iron powder produced in Example 2 in the same manner as in Example 2 without adding the polytetrafluoroethylene resin powder. After the presence or absence of this, the heat treatment which hold | maintains this compression molding to the temperature shown in Table 2 in air | atmosphere was performed, and the comparative method 2 was implemented.
The ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm prepared by Comparative Method 2 was measured in the same manner for the crushing strength, density, specific resistance, and magnetic flux density. The results are shown in Table 2.

  From the results shown in Table 2, the present invention method 2 is capable of producing a composite soft magnetic material having no defects in the compression-molded body as compared with the comparative method 2 and superior in strength to the conventional method 1 shown in Table 1. I understand that I can do it.

Example 3
Polyamide imide resin is dissolved in N-methylpyrrolidone, and polytetrafluoroethylene powder and atomized iron powder are added to this solution and stirred to disperse, and dried with stirring to perform primer treatment on the atomized iron powder surface. And a primer-treated atomized iron powder having the composition shown in Table 3 was prepared.
A polytetrafluoroethylene resin powder was added to the primer-treated atomized iron powder at a ratio shown in Table 3 and mixed to prepare a mixed powder. The mixed powder is filled in the inner space of the mold having an outer diameter of 35 mm, an inner diameter of 30 mm, and a depth of 25 mm without applying the lubricant to the inner surface of the mold, and is compressed by compression molding at a pressure of 780 MPa. After preparing a compression molded body having a thickness of 10 mm and checking the presence or absence of a defective product of the compression molded body, the compression molded body was subjected to heat treatment for maintaining the compression molded body at the temperature shown in Table 3 in the present invention. Carried out.
For the ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm manufactured by the method 3 of the present invention, the crushing strength at room temperature is measured by the Archimedes method using a universal testing machine. The density, the specific resistance of the C-shaped test piece obtained by dividing the ring-shaped test piece into two parts were measured by the four-terminal method, and the magnetic flux density was measured with a BH loop tracer after winding. The results are shown in Table 3.

Comparative Example 3
A compression-molded article was produced by compression-molding the primed atomized iron powder produced in Example 3 in the same manner as in Example 3 without adding polytetrafluoroethylene resin powder. After the presence or absence of this, the compression molding was subjected to heat treatment for holding the compressed molded body at the temperature shown in Table 3 in the atmosphere, and Comparative Method 3 was carried out.
For the ring-shaped composite soft magnetic material test piece having the outer diameter of 35 mm, the inner diameter of 30 mm, and the height of 10 mm produced by Comparative Method 3, the crushing strength, density, specific resistance and magnetic flux density were measured in the same manner. The results are shown in Table 3.

  From the results shown in Table 3, the present invention method 3 can produce a composite soft magnetic material having no defects in the compression-molded body as compared with the comparative method 3 and superior in strength to the conventional method 1 shown in Table 1. I understand that I can do it.

Example 4
Dissolve the polyimide resin in N-methylpyrrolidone, add polytetrafluoroethylene powder and atomized iron powder to this solution and stir to disperse, and dry with stirring to apply the primer treatment to the atomized iron powder surface. Primer-treated atomized iron powder having the composition shown in Table 4 was prepared.
A polytetrafluoroethylene resin powder was added to the primer-treated atomized iron powder at a ratio shown in Table 4 and mixed to prepare a mixed powder. The mixed powder is filled in the inner space of the mold having an outer diameter of 35 mm, an inner diameter of 30 mm, and a depth of 25 mm without applying the lubricant to the inner surface of the mold, and is compressed by compression molding at a pressure of 780 MPa. After preparing a compression molded body having a thickness of 10 mm and checking the presence or absence of defective products of the compression molded body, the compression molded body was subjected to heat treatment for holding the compressed molded body at the temperature shown in Table 4 in the atmosphere. Carried out.
The ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by the method 4 of the present invention was measured for the crushing strength at room temperature by using the Archimedes method. Table 4 shows the density, the specific resistance was measured by a four-terminal method on a C-shaped test piece obtained by dividing the ring-shaped test piece into two pieces, and the magnetic flux density was measured by a BH loop tracer.

Comparative Example 4
A compression-molded article was produced by compression-molding the primed atomized iron powder produced in Example 4 in the same manner as in Example 4 without adding polytetrafluoroethylene resin powder. After the presence or absence of this, the compression molding was subjected to heat treatment for holding the compressed molded body at the temperature shown in Table 4 in the atmosphere, and Comparative Method 4 was carried out.
With respect to the ring-shaped composite soft magnetic material test piece having the outer diameter of 35 mm, the inner diameter of 30 mm, and the height of 10 mm produced by Comparative Method 4, the crushing strength, density, specific resistance and magnetic flux density were measured in the same manner. The results are shown in Table 4.

  From the results shown in Table 4, the present invention method 4 is capable of producing a composite soft magnetic material having no defects in the compression-molded body as compared with the comparative method 4 and superior in strength to the conventional method 1 shown in Table 1. I understand that I can do it.

Example 5
Dissolve the liquid silicone resin in toluene, add polytetrafluoroethylene powder and atomized iron powder to this solution and stir to disperse, and dry with stirring to apply a primer treatment to the surface of the atomized iron powder. A primer-treated atomized iron powder having the composition shown in FIG.
A polytetrafluoroethylene resin powder was added to the primer-treated atomized iron powder at a ratio shown in Table 5 and mixed to prepare a mixed powder. The mixed powder is filled in the inner space of the mold having an outer diameter of 35 mm, an inner diameter of 30 mm, and a depth of 25 mm without applying the lubricant to the inner surface of the mold, and is compressed by compression molding at a pressure of 780 MPa. After preparing a compression molded body having a thickness of 10 mm and checking the presence or absence of defective products of the compression molded body, the compression molded body was subjected to heat treatment for holding the compression molded body at the temperature shown in Table 5 in the present invention. Carried out.
For the ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by the method 5 of the present invention, the crushing strength at room temperature was measured by the Archimedes method using a universal testing machine. The density was measured for the C-shaped test piece obtained by dividing the ring-shaped test piece into two parts by the four-terminal method, the winding was applied, and the magnetic flux density was measured by the BH loop tracer. The results are shown in Table 5.

Comparative Example 5
A compression-molded article was produced by compression-molding the primed atomized iron powder produced in Example 5 in the same manner as in Example 5 without adding polytetrafluoroethylene resin powder. After the presence or absence of this, the compression molding was subjected to heat treatment for holding the compressed molded body at a temperature shown in Table 5 in the atmosphere, and Comparative Method 5 was carried out.
With respect to the ring-shaped composite soft magnetic material test piece having the outer diameter of 35 mm, the inner diameter of 30 mm, and the height of 10 mm produced from Comparative Method 5, the crushing strength, density, specific resistance and magnetic flux density were measured in the same manner. The results are shown in Table 5.

  From the results shown in Table 5, the present invention method 5 is capable of producing a composite soft magnetic material having no defects in the compression-molded body as compared with the comparative method 5 and superior in strength to the conventional method 1 shown in Table 1. I understand that I can do it.

Example 6
Dissolve the polyethersulfone resin in N-methylpyrrolidone, add polytetrafluoroethylene powder and phosphate-coated iron powder to this solution and stir to disperse, and dry with stirring to cover the phosphate The surface of the iron powder was subjected to a primer treatment to prepare a primer-treated phosphate-coated iron powder having the composition shown in Table 6.
A polytetrafluoroethylene resin powder was added to the primer-treated phosphate-coated iron powder at a ratio shown in Table 6 and mixed to prepare a mixed powder. The mixed powder is filled in the inner space of the mold having an outer diameter of 35 mm, an inner diameter of 30 mm, and a depth of 25 mm without applying the lubricant to the inner surface of the mold, and is compressed by compression molding at a pressure of 780 MPa. Length: After producing a 10 mm compression molded body and examining the presence or absence of defective products of this compression molded body, the compression molded body was subjected to heat treatment for holding the compressed molded body at the temperatures shown in Table 6 in the present invention. Carried out.
The ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by the method 6 of the present invention was measured for the crushing strength at room temperature by using the Archimedes method using a universal testing machine. The density was measured for the C-shaped test piece obtained by dividing the ring-shaped test piece into two pieces by measuring the specific resistance by the four-terminal method, and the magnetic flux density was measured by the BH loop tracer after winding. The results are shown in Table 6.

Comparative Example 6
A compression-molded body was produced by compression-molding the primer-treated phosphate-coated iron powder produced in Example 6 in the same manner as in Example 6 without adding polytetrafluoroethylene resin powder. After the presence or absence of the defective product was examined, a comparative heat treatment was carried out by subjecting this compression-molded body to heat treatment in the atmosphere at a temperature shown in Table 6.
For the ring-shaped composite soft magnetic material test piece having the outer diameter: 35 mm, the inner diameter: 30 mm, and the height: 10 mm produced by Comparative Method 6, the crushing strength, density, specific resistance, and magnetic flux density were measured in the same manner. The results are shown in Table 6.

Conventional example 2
Polytetrafluoroethylene resin powder, which is a fluororesin powder, is mixed with phosphate-coated iron powder in the proportions shown in Table 6 to produce a mixed powder. This mixed powder is compression-molded in the same manner as in Example 6. After the compression molded body was manufactured and the presence or absence of defective products of the compression molded body was checked, the conventional method 6 was carried out by performing a heat treatment for holding the compression molded body at the temperature shown in Table 6 in the atmosphere. did.
For the ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by the conventional method 6, the crushing strength, density, specific resistance and magnetic flux density were measured in the same manner. The results are shown in Table 6.

  From the results shown in Table 6, the present invention method 6 can produce a composite soft magnetic material having no defects in the compression-molded body as compared with the comparative method 6 and superior in strength to the conventional method 2 shown in Table 6. I understand that I can do it.

Example 7
After adding polyphenylene sulfide resin, polytetrafluoroethylene powder and phosphate-coated iron powder to ethanol and dispersing by stirring, drying with stirring, holding the dried powder at 350 ° C. in air for 30 minutes, By crushing the agglomerated powder, the surface of the phosphate-coated iron powder was subjected to a primer treatment to prepare a primer-treated phosphate-coated iron powder having the composition shown in Table 7.
Polytetrafluoroethylene resin powder was added to the primer-treated phosphate-coated iron powder at a ratio shown in Table 7 and mixed to prepare a mixed powder. The mixed powder is filled in the inner space of the mold having an outer diameter of 35 mm, an inner diameter of 30 mm, and a depth of 25 mm without applying the lubricant to the inner surface of the mold, and is compressed by compression molding at a pressure of 780 MPa. After preparing a compression molded body having a thickness of 10 mm and checking the presence or absence of defective products of the compression molded body, the compression molded body was subjected to heat treatment for holding the compressed molded body at the temperatures shown in Table 7 in the present invention. Carried out.
For the ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by the method 7 of the present invention, the crushing strength at room temperature was measured by the Archimedes method using a universal testing machine. The density was measured for the C-shaped test piece obtained by dividing the ring-shaped test piece into two parts by the four-terminal method, and the magnetic flux density was measured using a BH loop tracer after winding. The results are shown in Table 7.

Comparative Example 7
A compression-molded body was produced by compression-molding the primer-treated phosphate-coated iron powder produced in Example 7 in the same manner as in Example 7 without adding polytetrafluoroethylene resin powder. After the presence or absence of the defective product was examined, the compression molded body was subjected to a heat treatment for holding the compressed molded body at the temperature shown in Table 7 in the atmosphere, and Comparative Method 7 was carried out.
For the ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by Comparative Method 7, the crushing strength, density, specific resistance and magnetic flux density were measured in the same manner. The results are shown in Table 7.

  From the results shown in Table 7, the present invention method 7 can produce a composite soft magnetic material having no defects in the compression-molded body as compared with the comparative method 7 and superior in strength compared with the conventional method 2 shown in Table 6. I understand that I can do it.

Example 8
Phosphate-coated iron is prepared by dissolving polyamideimide resin in N-methylpyrrolidone, dispersing polytetrafluoroethylene powder and phosphate-coated iron powder in this solution by stirring, and drying while stirring. The powder surface was subjected to a primer treatment to prepare a primer-treated phosphate-coated iron powder having a composition shown in Table 8.
A polytetrafluoroethylene resin powder was added to the primer-treated phosphate-coated iron powder at a ratio shown in Table 8 and mixed to prepare a mixed powder. The mixed powder is filled in the inner space of the mold having an outer diameter of 35 mm, an inner diameter of 30 mm, and a depth of 25 mm without applying the lubricant to the inner surface of the mold, and is compressed by compression molding at a pressure of 780 MPa. After preparing a compression molded body having a thickness of 10 mm and examining the presence or absence of defective products of the compression molded body, the compression molded body was subjected to a heat treatment for holding the compression molded body at the temperature shown in Table 8 in the present invention. Carried out.
For the ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by the method 8 of the present invention, the crushing strength at room temperature was measured by the Archimedes method using a universal testing machine. The density was measured for the C-shaped test piece obtained by dividing the ring-shaped test piece into two parts by measuring the specific resistance by the four-terminal method, and the magnetic flux density was measured by the BH loop tracer after winding. The results are shown in Table 8.

Comparative Example 8
A compression-molded body was produced by compression-molding the primer-treated phosphate-coated iron powder produced in Example 8 in the same manner as in Example 8 without adding polytetrafluoroethylene resin powder. After the presence or absence of the defective product, the compression molding was subjected to heat treatment for holding the compressed molded body at a temperature shown in Table 8 in the atmosphere, and Comparative Method 8 was carried out.
For the ring-shaped composite soft magnetic material test piece having the outer diameter of 35 mm, the inner diameter of 30 mm, and the height of 10 mm produced by Comparative Method 8, the crushing strength, density, specific resistance and magnetic flux density were measured in the same manner. The results are shown in Table 8.

  From the results shown in Table 8, the present invention method 8 can produce a composite soft magnetic material having no defects in the compression-molded body as compared with the comparative method 8 and superior in strength to the conventional method 2 shown in Table 6. I understand that I can do it.

Example 9
Dissolve polyimide resin in N-methylpyrrolidone, add polytetrafluoroethylene powder and phosphate-coated iron powder to this solution and stir to disperse, and dry with stirring to phosphate-coated iron powder The surface was subjected to a primer treatment to prepare a primer-treated phosphate-coated iron powder having the composition shown in Table 9.
A polytetrafluoroethylene resin powder was added to the primer-treated phosphate-coated iron powder at a ratio shown in Table 9 and mixed to prepare a mixed powder. The mixed powder is filled in the inner space of the mold having an outer diameter of 35 mm, an inner diameter of 30 mm, and a depth of 25 mm without applying the lubricant to the inner surface of the mold, and is compressed by compression molding at a pressure of 780 MPa. After preparing a compression molded body having a thickness of 10 mm and checking the presence or absence of defective products of the compression molded body, the compression molded body was subjected to heat treatment for holding the compressed molded body at a temperature shown in Table 9 in the air. Carried out.
The ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by the method 9 of the present invention was measured for the crushing strength at room temperature by using the Archimedes method using a universal testing machine. The density was measured on the C-shaped test piece obtained by dividing the ring-shaped test piece into two parts by the four-terminal method, and the magnetic flux density was measured with a BH loop tracer after winding. The results are shown in Table 9.

Comparative Example 9
A compression-molded body was prepared in the same manner as in Example 9 without adding the polytetrafluoroethylene resin powder to the primer-treated phosphate-coated iron powder prepared in Example 9, and the presence or absence of a defective product of this compression-molded body was checked. After the investigation, the compression molding was subjected to a heat treatment for holding at a temperature shown in Table 9 in the atmosphere, and Comparative Method 9 was performed.
The ring-shaped composite soft magnetic test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by Comparative Method 9 was measured in the same manner to measure the crushing strength, density, specific resistance, and magnetic flux density. The results are shown in Table 9.

  From the results shown in Table 9, the present invention method 9 is capable of producing a composite soft magnetic material having no defects in the compression-molded body as compared with the comparative method 9 and superior in strength to the conventional method 2 shown in Table 6. I understand that I can do it.

Example 10
Dissolve the liquid silicone resin in toluene, add polytetrafluoroethylene powder and phosphate-coated iron powder to this solution and stir to disperse, and dry with stirring to the phosphate-coated iron powder surface. Primer treatment was performed to prepare a primer-treated phosphate-coated iron powder having a composition shown in Table 10.
A polytetrafluoroethylene resin powder was added to the primer-treated phosphate-coated iron powder at a ratio shown in Table 10 and mixed to prepare a mixed powder. The mixed powder is filled in the inner space of the mold having an outer diameter of 35 mm, an inner diameter of 30 mm, and a depth of 25 mm without applying the lubricant to the inner surface of the mold, and is compressed by compression molding at a pressure of 780 MPa. A 10 mm compression molded body was prepared, and the presence or absence of a defective product of the compression molded body was examined. After that, the compression molded body was subjected to a heat treatment for holding at a temperature shown in Table 10 in the atmosphere. Carried out.
The ring-shaped composite soft magnetic material test piece having an outer diameter of 35 mm, an inner diameter of 30 mm, and a height of 10 mm produced by the method 10 of the present invention was measured for the crushing strength at room temperature by using the Archimedes method using a universal testing machine. The density, the specific resistance of the C-shaped test piece obtained by dividing the ring-shaped test piece into two parts, and the magnetic flux density were measured with a BH loop tracer after winding, and the results are shown in Table 10.

Comparative Example 10
A compression-molded body was produced by compression-molding the primer-treated phosphate-coated iron powder produced in Example 10 in the same manner as in Example 10 without adding polytetrafluoroethylene resin powder. After the presence or absence of the defective product was examined, the compression molding was subjected to a heat treatment for holding the compressed molded body at a temperature shown in Table 10 in the atmosphere, and Comparative Method 10 was carried out.
For the ring-shaped composite soft magnetic material test piece having the outer diameter of 35 mm, the inner diameter of 30 mm, and the height of 10 mm produced from Comparative Method 10, the crushing strength, density, specific resistance and magnetic flux density were measured in the same manner. The results are shown in Table 10.

  From the results shown in Table 10, the present invention method 10 can produce a composite soft magnetic material having no defects in the compression-molded body as compared with the comparative method 10 and superior in strength to the conventional method 2 shown in Table 6. I understand that I can do it.

Claims (5)

The surface of iron powder or iron powder with a phosphate film formed on the surface (hereinafter referred to as phosphate-coated iron powder) is preliminarily subjected to primer treatment, and the phosphate-coated iron powder subjected to this primer treatment is then subjected to fluororesin powder. A method for producing a composite soft magnetic material having high strength and high specific resistance is characterized in that a mixed powder is prepared by adding and mixing, and the mixed powder is compression-molded and then subjected to heat treatment. In the primer treatment, a liquid in which polytetrafluoroethylene and one or more of polyethersulfone, polyphenylene sulfide, polyamideimide, polyimide, and silicone resin and polytetrafluoroethylene are dissolved or dispersed is applied to the surface of iron powder or phosphate-coated iron powder. 2. The method for producing a composite soft magnetic material having high strength and high specific resistance according to claim 1, wherein the treatment is applied and dried. The mixed powder prepared by adding and mixing fluororesin powder to the iron powder or phosphate-coated iron powder subjected to the primer treatment is obtained by adding the fluororesin powder to the iron powder or phosphate-coated iron powder subjected to the primer treatment. 3. The method for producing a composite soft magnetic material having high strength and high specific resistance according to claim 1, wherein the mixed powder is obtained by adding 0.1 to 1.5% by mass and mixing. The method for producing a composite soft magnetic material having high strength and high specific resistance according to claim 1, 2 or 3, wherein the heat treatment is performed by heating in a temperature range of 320 to 450 ° C. A composite soft magnetic material having high strength and high specific resistance, which is produced by the method according to claim 1, 2, 3 or 4.